Geology of Wind River Canyon, Wyoming (cont.)
4 Cambrian Rocks
Cambrian rocks are represented by the Gallatin limestone, the Gros Ventre formation and the Flathead sandstone.
Figure 4-1. Northern end of the Gallatin limestone outcrop.
View to the northwest at 43° 32' 01" N. Cambrian Gallatin limestone unconformably underlies Bighorn dolomite. Mm : Mississippian Madison limestone. Ob : Ordovician Bighorn dolomite. _g : Cambrian Gallatin limestone (limestone, argillaceous
limestone, and silty calcareous claystone); thickness is variable (~140 m) as well as resistance to erosion, depending on composition. Dotted line : unconformity.
Figure 4-2. Madison limestone, Bighorn dolomite and Gallatin limestone in the Wind River canyon.
View to the north of the eastern side of Wind River canyon at 43° 30' 26" N. The Madison limestone and the thin Bighorn dolomite form the cliff at the top and the Gallatin limestone the slope at the bottom.
Figure 4-3. Gallatin limestone and Gros Ventre formation in the Wind River canyon.
View to the northwest of the western side of Wind River canyon at 43° 28' 46" N. Here the exposed part of the Gallatin limestone is more competent and forms a steep cliff. It conformably overlies the Gros Ventre formation, which consists mostly of mudstone, but also of some claystone, limestone and sandstone; it generally forms slopes, but the more resistant beds appear as ledges. _g : Cambrian Gallatin limestone. _gv : Cambrian Gros Ventre formation (~120 m thick). Dashed line: conformable layer boundary.
Figure 4-4. Northernmost exposure of Cambrian Flathead sandstone in the Wind River canyon.
View to the northwest at 43° 28' 21" N. Flathead sandstone is the oldest Paleozoic rock in the Wind River canyon. Ledges in the Gros Ventre formation are well visible in this photo. _g : Cambrian Gallatin limestone. _gv : Cambrian Gros Ventre formation. _f : Cambrian Flathead sandstone (arkosic and micaceous
quartz arenite; 80 m thick). Dashed lines: conformable layer boundaries.
Figure 4-5. Flathead sandstone in the Wind River canyon.
View at at 43° 28' 04" N. Although looking similar to the preceding photo, this one is taken ~600 m more to the south. The Flathead sandstone has a general light orange color, becoming redder with hematite and grayer with siltstone..